The invention relates to an apparatus for establishing a routine shot distance of a taking lens of a camera, and more particularly, to such apparatus in which the taking lens is automatically moved to its routine shot distance in interlocked relationship with the opening/closing of a lens protective cover of the camera.
A photographic camera is already known having a lens protective cover which is movable between a first position covering a taking lens and a second position where the taking lens is exposed and which is provided with a device for automatically bringing the taking lens to a position corresponding to a normal focussed distance as the protective cover is opened/closed.
FIG. 1 illustrates an example of a camera which is provided with such device for establishing a normal focussed distance of a taking lens. Camera 1 includes a body 2 having a front surface in which a taking lens 3 is centrally located, and is associated with a lens protective cover 4 which is movable between a first position where it covers the taking lens 3 and a second position where it allows the taking lens to be exposed. The protective cover includes a front wall which is located opposite to the front surface of the body 2 and which is disposed along the right-hand half of the body 2 so as to be slidable in the horizontal direction along the front surface of the body 2. It will be noted that the front wall is centrally formed with a semi-circular bulge 4a which projects forwardly from its left-hand edge, as viewed in FIG. 1, so as to avoid its abutment against a lens frame 16 which slightly projects beyond the front surface of the body 2, as the protective cover is moved to its lens covering position.
An abutment frame 5 is integrally formed with the body 2 at a location to the left of the taking lens 3 so that the left-hand edge of the protective cover 4 may abut against it whenever it has moved to its closed position. Again, it will be noted that the abutment frame 5 is centrally formed with a semi-circular bulge 5a which extends from its right-hand edge and projecting forwardly. It will be seen that the combination of the semi-circular bulges 5a, 4a is effective to define a unitary oblong configuration when the protective cover 4 closes the taking lens 3.
It is to be understood that the lens protective cover 4 is arranged to cover, not only the taking lens 3, but also a light receiving window 6 which is used for photometric purpose and located directly above the lens 3, an objective window 7 for viewfinder which is located directly above the window 6, a film speed presetting knob 8 located directly below the taking lens 3 and a flash photography select knob 9 which is located below the knob 8 simultaneously. Consequently, when the lens protective cover 4 is moved to its open position where the exposure of the taking lens 3 is allowed, all of the windows 6, 7, and knobs 8, 9 are exposed through the front surface of the body 2.
Also disposed on the front surface of the body 2 at a location toward the left-hand end thereof and also to the left of the abutment frame 5 is a distance selecting assembly 11 including a knob 12 which is used to establish a desired focussed position for the taking lens 3 and three zone focus pictorial indices 14, with which the knob 12 is brought into alignment. In FIG, 1, numeral 15 indicates a light window for indicating a self-timer and battery checker.
FIG. 2 shows an example of a conventional arrangement for establishing a normal focussed distance which may be used in the camera 1, shown in FIG. 1. The apparatus shown comprises a distance select member 21 integrally carrying the knob 12, a distance ring 22 disposed for rotation as the distance select member 21 is moved up and down, a drive member 23 for causing a fore-and-aft movement of the taking lens 3 (FIG. 1) along the optical axis in response to rotation of the distance ring 22, a return arm 24 for returning the distance ring 22 to a given position as the lens protective cover 4 is closed, and a leaf spring 25 which defines a click stop for locking the distance ring 22 at its home position.
The distance select member 21 is a strip member of crisscross form, with the knob 12 formed on the left-hand free end of the longitudinal portion. The right-hand end of the longitudinal portion is formed into a fork 21a, engaged by an operating pin 26 which is fixedly mounted on the front surface of the distance ring 22 at a corresponding position. In addition, the distance select member 21 includes a pair of upper and lower lateral extensions in which laterally elongate guide slots 21b, 21c are formed respectively. It is to be understood that these slots are engaged by stationary pins, not shown. In this manner, by operating the knob 12, the distance select member 21 may be moved up and down as such movement is guided by the cooperation between the slots 21b, 21c and the stationary pins.
The distance ring 22 is in the form of an annular disc in which the lens frame or barrel 16 (FIG. 1) of the taking lens 3 is loosely fitted. In addition to the operating pin 26, the distance ring 22 includes an L-shaped member 22a extending from its periphery at an advanced position with respect to the pin 26, as viewed counter-clockwise in FIG. 2. The member 22a is engageable with a step 4c formed on the rear side of the lens protective cover 4. The drive member 23 is secured to the front surface of the distance ring 22 at a position further advanced counter-clockwise than the L-shaped member 22a. The drive member 23 has an L-shaped extension at its one end which projects forwardly, with the free end of the extension being formed into a fork 23a which is engaged by a driven pin 27 fixedly mounted on the outer peripheral surface of the lens barrel 16 (FIG. 1) of the taking lens 3. Accordingly, as the distance ring 22 rotates, the barrel 23 also rotates to cause a fore-and-aft movement of the taking lens 3 along the optical axis for purpose of distance adjustment.
At a position which is lagging behind the operating pin 26, as viewed counter-clockwise in FIG. 2, the outer periphery of the distance ring 22 is formed with a notch 22b, which is engageable with the V-shaped end of the leaf spring 25 when the distance ring 22 assumes its home position, thus defining a click stop. At a position further lagging behind the notch 22b, the distance ring 22 fixedly carries a driven pin 28 on its front surface which is adapted to bear against the return arm 24 to be driven in the returning direction.
The return arm 24 is again formed by a strip member having branched or forked ends while its opposite end is pivotally mounted on a stationary pin 29. Its left-hand arm 24a is disposed so that its left-hand end face is located opposite to the driven pin 28 while its right-hand arm 24b has its free end folded to project forwardly so as to be engageable with the step 4b formed on the rear side of the protective cover 4. The right-hand arm 24b is engaged by one end of a coiled tension spring 31, whereby the return arm 24 is urged to rotate clockwise about the pin 29. However, the resulting angular movement of the arm 24 is limited by the abutment of the right-hand side of the arm 24b against a stop pin 32 which is fixedly mounted on a stationary member, not shown, whenever the lens protective cover 4 assumes its open position.
In operation, when the lens protective cover 4 is brought to its open position where the taking lens 3 is exposed, the steps 4b, 4c formed on the cover 4 move out of engagement with associated members, so that the resilience of the spring 31 permits the return arm 24 to be disengaged from the driven pin 28, clockwise rotating about the pin 29 until it bears against the stop pin 32,. This frees the distance ring 22 from any constraint by the cover 4, and the ring 22 becomes movable angularly with a reduced force which is sufficient to overcome the resilience of the leaf spring 25. Hence, the knob 12 may be operated under this condition, causing a corresponding rotation of distance ring 22 to thereby rotate the lens barrel 16 through the drive member 23 and the driven pin 27, thus moving the taking lens 3 fore-and-aft along the optical axis. Hence, when the knob 12 is aligned with one of the indices 14 corresponding to a desired distance, the camera can be freely established so that the taking lens 3 is focussed to a desired distance. Hence, it is only necessary that the user of the camera depresses a shutter release button, not shown, whereupon a properly focussed photograph can be taken.
Upon completion of a photographing operation, the lens protective cover 4 may be moved to its closed position, whereupon either or at least one of the steps 4b, 4c on the cover 4 engage the return arm 24 and/or the L-shaped member 22a to cause the return arm 24 to be engaged with the driven pin 28 against the resilience of the spring 31, thus returning the distance ring 22 to its home position. In this manner, the knob 12 is moved into alignment with one of the indices 14, shown as a whole figure and corresponding to a normal focussed distance of 3 m, and the cooperation of the drive member 23 and the driven pin 27 is effective to establish a normal focussed distance of 3 m for the taking lens 3 automatically.
FIG. 3 shows another example of apparatus for establishing a normal focussed distance. In this apparatus, the use of the L-shaped member 22a and return arm 24 to return the distance ring 22 to its home position as illustrated in the arrangement of FIG. 2 is replaced by the use of a cam plate 44 and a follower pin 48, which are also effective to return a distance ring 42 to its home position.
The cam plate 44 is disposed on the rear side of the lens protective cover 4, and has a V-shaped notch formed in its left-hand edge which has a width comparable to the outer diameter of the distance ring 42. The notch defines a pair of cam surfaces 44a, 44b. The follower pin 48 is fixedly mounted on the front surface of the distance ring 42, again in the form of an annular disc, at a location corresponding to the bottom of the notch as viewed in FIG. 3.
Other members correspond to those shown in FIG. 2, and hence these members are designated by numerals corresponding to those used in FIG. 2 and to which 20 is added, without repeating their description.
In this arrangement, if the focal length of the taking lens 3 is preset to a shorter distance than 3 m which represents the normal focussed distance when the lens protective cover assumes its open position, the distance ring 42 has rotated counter-clockwise from its home position, so that the follower pin 48 has moved upward from its home position. Accordingly, when the lens protective cover 4 is closed from this condition, the cam plate 44 moves to the left together with the cover 4, causing the follower pin 48 to move down while maintaining it in abutment against the upper cam surface 44a. Accordingly, the distance ring 42 rotates clockwise until its home position is reached while the cooperation between the drive member 43 and driven pin 47 automatically establishes a normal focussed position of the taking lens 3.
If the focal length of the taking lens 3 is established at a value greater than 3 m which represents the normal focussed distance when the lens protective cover assumes its open position, the distance ring 42 has rotated clockwise from its home position, and hence the follower pin 48 has moved down from its home position. When the lens protective cover 4 is closed under this condition, a movement of the cam plate 44 to the left together with the cover 4 causes the follower pin 48 to be raised upward to its home position while maintaining it in abutment against the lower cam surface 44b. Hence, the distance ring 22 rotates counter-clockwise until the home position is reached, whereby the taking lens 3 is returned to its normal focussed position automatically.
It will be therefore seen that the taking lens 3 is returned to its normal focussed position automatically as the lens protective cover 4 is closed, irrespective of the previous focal length of the taking lens 3 which the latter assumed before the shutter is closed.
It will be seen from the foregoing description that with the camera 1 having the apparatus illustrated in FIG. 2 or FIG. 3 disposed therein, the normal focussed position of the taking lens 3 is automatically established as the lens protective cover 4 is opened, so that a picture can be taken without any substantial defocussing effect of almost any object being photographed immediately upon opening the protective cover 4, without requiring any distance adjustment.
However, it will be appreciated that when such camera 1 is used to take pictures of children indoors, the use of an electronic flash is almost essential in view of the brightness factor in order to assure a proper photograph. Hence, a picture is taken in this instance by maintaining the diaphragm open, with consequence that the depth of field of the taking lens 3 is reduced. If an object being photographed is located at a small distance, there might result a defocussed photograph with a rear focus. In addition, with camera 1 using the normal size 35 mm roll film such as a small type having a lens shutter, an object being photographed, such as children is placed in a manner corresponding to the normal focussed distance, the image of the object will be too small in the image field. Hence, the object must be located at a reduced or minimum distance, further contributing to the likelihood that a defocussed photograph with the rear focus may result.
It will be noted that when a flash photography of an object located at minimum distance is attempted with the camera 1, the taking lens 3 may be readjusted from its normal focussed position to its minimum distance before taking a picture. However, such operation is troublesome and the user of the camera has a prejudice that the camera is an auto pan-focus, which causes the user to forget the necessity of such readjustment, frequently resulting in the drawback that defocussed pictures are taken.